Table 1. Design-of-experiments variation of parameters.
Several user-defined parameters were selected factorial experiment optimization: (A) the RF voltage of the DMS sensor (1200 V or 1400V); (B) nitrogen carrier gas flow rate through the DMS (250 or 500 mL min−1); (C) solid phase microextraction (SPME) filter type (Polyacrylate or PDMS-DVB); (D) GC cooling profile (cryogenic and non-cryogenic). A total of 16 different combinations of instrument settings were tested with n=3 replicates for each configuration. Plus signs denote where the larger values of each parameter are used, whereas minus signs require the use of lower parameter value. Signs of the interactions are determined by the resulting sign of the multiple of interacting variables. Two outputs are measured: total number of chemical peaks (Y), and the amplitude of acetone peak (Z).
| Factor | Interaction of factors | Outputs | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Config. | A | B | C | D | AB | AC | AD | BC | BD | CD | ABC | ABD | BCD | ABCD | Y (avg) | Y (std) | Z (avg) | Z (std) |
| 1 | + | + | + | + | + | + | + | + | + | + | + | + | + | + | 332 | 6.9 | .1200 | 0.0005 |
| 2 | + | + | + | − | + | + | − | + | − | − | + | − | − | − | 361 | 35.1 | .1193 | 0.0005 |
| 3 | + | + | − | + | + | − | + | − | + | − | − | + | − | − | 313 | 28.3 | .1196 | 0.0003 |
| 4 | + | + | − | − | + | − | − | − | − | + | − | − | + | + | 335 | 14.1 | .1192 | 0.0005 |
| 5 | + | − | + | + | − | + | + | − | − | + | − | − | − | − | 245 | 104.2 | .1186 | 0.0001 |
| 6 | + | − | + | − | − | + | − | − | + | − | − | + | + | + | 388 | 70.8 | .1188 | 0.0002 |
| 7 | + | − | − | + | − | − | + | + | − | − | + | − | + | + | 264 | 61.8 | .1191 | 0.0002 |
| 8 | + | − | − | − | − | − | − | + | + | + | + | + | − | − | 370 | 58.8 | .1186 | 0.0004 |
| 9 | − | + | + | + | − | − | − | + | + | + | − | − | + | − | 137 | 5.0 | .1210 | 0.0002 |
| 10 | − | + | + | − | − | − | + | + | − | − | − | + | − | + | 126 | 3.2 | .1195 | 0.0004 |
| 11 | − | + | − | + | − | + | − | − | + | − | + | − | − | + | 133 | 9.0 | .1196 | 0.0001 |
| 12 | − | + | − | − | − | + | + | − | − | + | + | + | + | − | 137 | 3.2 | .1191 | 0.0003 |
| 13 | − | − | + | + | + | − | − | − | − | + | + | + | − | + | 258 | 18.9 | .1192 | 0.0002 |
| 14 | − | − | + | − | + | − | + | − | + | − | + | − | + | − | 202 | 75.6 | .1194 | 0.0002 |
| 15 | − | − | − | + | + | + | − | + | − | − | − | + | + | − | 224 | 22.2 | .1188 | 0.0002 |
| 16 | − | − | − | − | + | + | + | + | + | + | − | − | − | + | 233 | 90.0 | .1188 | 0.0004 |